Modeling of the Tunneling Current in MOS Devices After Proton Irradiation Using a Nonlinear Series Resistance Correction

Contrary to what is expected for a damaged device, the impact of 10 MeV-energy protons on a metal-oxide-semiconductor (MOS) structure can give rise to a significant reduction of the gate tunneling current, mainly in the high bias range. In order to simulate the observed deviation, a correction to the oxide field in the Fowler-Nordheim tunneling expression is considered. Since the nature and location of the device damaged region have not been clearly identified yet, the conduction problem is circumvented by introducing an effective nonlinear series resistance correction. Experimental and simulated data obtained as a function of the irradiation fluences supporting the proposed approach are presented. The possible origin of this nonlinear resistance and its implications for the reliability assessment of irradiated MOS devices are also discussed.